Conventional operating frequency bands of a mobile communications system are mainly frequency bands below 3 GHz. As a result, spectrum resources are very limited. To implement ultrafast short-range communication and support 5G requirements for a capacity, a transmission rate, and the like, a signal is transmitted in the mobile communications system by using a high frequency band, to mitigate current shortage of spectrum resources. To overcome a native disadvantage, that is, a high path loss, of the high frequency band, a high-gain narrow-beam antenna needs to be used at a physical layer to improve link coverage. Beam scanning is inevitable in high-frequency communication. In the beam scanning, excitation phases of array elements are changed by using a method for controlling a phase shift amount of a phase shifter, so as to implement the beam scanning.
In a beam scanning process in the prior art, a switching gap is reserved for each beam switching time, and no signal is sent in a time period of the switching gap, thereby wasting overheads.